This invention relates to a reclining dental examination and treatment chair, hereinafter called a dental recliner, and more particularly, to such a dental recliner which tilts to position the patient's head at the desired height.
In the past, dental recliners have utilized a fairly conventional chair having an articulated back and an articulated foot and leg support mechanism. A patient was required to sit on the seat portion which was, generally, adjustable in height. After the patient was seated, the articulated back was lowered, allowing the patient's head, shoulders and back to assume a supine position more or less on horizontal with the buttocks of the patient. The patient's legs were raised and supported in a comfortable position by the leg support mechanism. Dental examination and treatment then proceeded with adjustments being made in the location of the patient's head and body as required to accomodate the dentist's need for access, and to maintain a somewhat comfortable working position for the dentist. Since the back of the conventional dental chair has a fixed radius and pivots from a fixed radius point, only a small range of sizes of patients and could be accurately and comfortably supported.
If an unusually tall or unusually short person were to use the chair, the adjustments of the chair would be required to extend to their maximum or minimum limits, respectively, with the result that the patient would not be comfortably and accurately positioned. In some cases, the dentist would be required to assume an extremely uncomfortable and tiring working position because of the inability of the conventional chair to support the patient in the desired location.
As a consequence of the wide range of hip to head distances which the chair had to accomodate, the entire chair was required to be raised or lowered in order to position the patient's head at the required working level.
In the supine position, the back of the conventional chair was cantilevered from the seat and supported a large percentage of the patient's weight. To achieve necessary stability, the chair and the pivot mechanism had to be extremely rigid. The result of this requirement was that the structural elements of the chair were extremely massive. Because the weight of the chair and the patient were unmanageably heavy, a mechanically-assisted lifting mechanism was usually employed which increased the cost of manufacture and was slow to adjust to the desired working position. These two factors in combination caused the conventional dental chair to be inefficient in use of materials and expensive to manufacture.
A need, therefore, exists for a reclining dental chair which is economical to manufacture, easy to operate, and adjustable to the wide variety of human forms, sizes, and weights which it must accomodate.